This paper is based on a research developed in a municipal public health unit of Belo Horizonte, Minas Gerais (Brazil). The objective was to follow the implantation of family planning groups, involving a low-income population. It was observed that women were the great majority in the groups. Some interviews with the women and professionals of the referred program have shown that the prevalence of female individuals in the groups was related to cultural values, as well as to the management of that health unit. However, it did not mean the women had the autonomy to choose their contraceptive method. They remained submitted to their sexual partner´s choice. The research also showed some mistakes and gaps in the public policies, not only in its proposal text, but also in the procedures of its implantation. It suggests an ambiguity among the practices linked to the construction of birth control rights in Brazil.